Growth in wireless communications has been driven by wideband communications of more than 10 Giga Hertz (GHz). FIG. 1 depicts the frequency spread of several wireless communication techniques. As shown, Terrestrial Trunked Radio (TETRA) is labeled 102; Global System for Mobile Communications 900 (GSM 900) is labeled 104; GSM 1800 is labeled 106; 3rd generation Mobile System (3G) is, labeled 108; Wireless Local Area Network 802.11b/g (WLAN 802.11b/g) is labeled 110; WLAN 802.11a is labeled 112; Ultrawideband (UWB) is labeled 114; and Wireless High Definition (wireless HD) is labeled 116. As shown, available communications frequencies reach 60 GHz.
For high frequency communications, advanced manufacturing processes is required for manufacturing transmitters and receivers. Thus, production cost is increased. Meanwhile, maintaining the bandwidth of a communications system is an important issue. However, it is very difficult and costly to both provide high frequency communications and wideband communications.